docs: def get_surface_boundaries(self):
          """
          Returns the boundaries in the same format as a multiplanar
          surface, with two one-element lists of lons and lats
          """
          mesh = self.mesh
          lons = numpy.concatenate((mesh.lons[0, :],
                                    mesh.lons[1:, -1],
                                    mesh.lons[-1, :-1][::-1],
                                    mesh.lons[:-1, 0][::-1]))
          lats = numpy.concatenate((mesh.lats[0, :],
                                    mesh.lats[1:, -1],
                                    mesh.lats[-1, :-1][::-1],
                                    mesh.lats[:-1, 0][::-1]))
          return [lons], [lats]